This is, in my opinion, a massive problem and one that the companies selling digital media will need to address at some point.
I would quite like to be able to subscribe to programs, ala iTunes Season Pass, and download high definition copies. All my music is digital now and I tend to prefer a digital format for my videos as well. I currently have a 1tb hard drive onto which I burn my DVDs so that on one device I have my entire collection.
But this is not practical really. It doesn't connect to a network in order to steam the media to many devices and space will eventually become a problem again which would require more external hard drives and it all becomes a mess!
How are we going to be able to have a fully digital media collection? How can this work when a typical HD 45 minute TV show is at least a gig in size?
I see two solutions: Home media servers or, when connections are fast enough, our media stored in the cloud. Maybe one subscription opens up a world on demand media. How do you stores yours, how would you?